Structure and circuit topology for a remotely actuated bypass splitter

ABSTRACT

The present invention is directed to a remotely actuated splitter bypass function (RASB) working in conjunction with a test head at the central office for testing and maintaining copper loops in the digital subscriber line environment. The RASB allows a competitive local exchange carrier to test and maintain the xDSL portion of the copper loop with minimal interference and disturbance to/from the plain old telephone system (POTS) service by bypassing the central office splitter. The splitter bypass operation includes the steps of selecting a copper loop pair for testing, actuating a first relay for monitor mode, actuating a second relay for bypass mode, testing the selected copper loop, and resetting the first and second relays back to normal mode. By applying positive and negative voltages from the tip and ring with respect to ground, various relays can be set (actuated) and reset to provide multiple modes of operations. In this manner, relays can be designed to respond in certain voltage levels and polarities.

This is a divisional application of U.S. Ser. No. 09/516,345 filed Mar.1, 2000.

FIELD OF THE INVENTION

The present invention relates to a remotely actuated splitter bypasssystem and method for testing and maintaining a copper loop. Moreparticularly, the present invention is directed to a system and methodfor remotely actuating a bypass function in a splitter such that testingand maintenance can be performed by a local exchange carrier withoutinterference to/from the plain old telephone system (POTS) service. Inparticular, the present invention discloses systems and methods allowinga competitive local exchange carrier (CLEC) to access the copper loopfor testing and maintenance with minimal interference to/from the POTSservice.

BACKGROUND OF THE INVENTION

In 1999, the Federal Communications Commission (FCC) adopted rules topromote competition between local telephone companies and providers ofhigh speed Internet access and other data services by directing thetelephone companies to share their telephone lines with such providers.With these rules, many companies can deploy new technologies on afaster, more cost-effective basis, thereby allowing residential andbusiness customers to access broadband and POTS services from a choiceof different providers.

Digital Subscriber Line or XDSL is one of the most promising newtechnologies for delivering superior service and higher speedconnections over existing infrastructure. Recent changes in thetelecommunications industry such as the deregulation of local marketshave brought on the emergence of new technologies such as xDSL. Inaddition, the growing demand for faster, more reliable Internet accesshas increased the demand for technologies that deliver higher speedconnections over existing infrastructure.

As known, different competing forms of digital subscriber linetechnologies are collectively designated as xDSL technologies with the“x” representing various one or more letter combinations, which are usedin front of the “DSL” acronym to designate the type of technology beingused. Some of the more prevalent xDSL technologies include HDSL, ADSL,SDSL, RADSL, VADSL, and VDSL.

xDSL uses the existing copper loop that is traditionally used forconventional telephony to deliver data at high bandwidth. Currently, thetransmission rates for xDSL technologies are dependent on the distancebetween a central office and a particular customer. Depending on thetype of xDSL technology, the transmission rate downstream to thecustomer and upstream to the central office may vary. Also, xDSL usespacket switching technology that operates independently of the voicetelephone system, allowing telephone companies to provide Internetservice and not lock up circuits for telephone calls. xDSL can carryboth voice and data signals simultaneously, in both directions, allowingthe customer to log onto the Internet and make a telephone call at thesame time. Thus, it is easy to understand why xDSL is becoming thepreferred system and method for sending/receiving analog and digitaldata/signals in the telecommunications industry.

Traditionally, incumbent local exchange carriers (ILECs) used theexisting copper loop for voice telephone and data services. With theadoption of the new FCC rules, competitive local exchange carriers(CLECS) can obtain access to the high-frequency portion of the localloop from the ILECs. This enables the CLECs to provide xDSL servicesover the same telephone lines simultaneously used by the ILECs, whichtechnique is know as “line sharing.”

Line sharing allows customers to obtain data service from either theILEC or CLEC without having to forego the traditional voice service fromtheir current provider. Line sharing also allows customers to receiveboth voice and data services on the same line; thus, eliminating theneed for customers to procure a second line. In other words, linesharing involves the CLEC providing xDSL service on the same copper loopon which the ILEC provides POTS service. As a result, this allows for amore efficient use of the existing telephone infrastructure by allowingCLECs to take advantage of the large installation base that alreadyexists.

One major shortcoming of the current line sharing system and method isthe testing and maintenance of the copper loop for the CLECs. Thisproblem is better understood by describing the current line sharingsystem and method, which is described in greater detail with referenceto FIGS. 1-2.

FIG. 1 illustrates a simplified diagram of a conventional line sharingsystem. In the conventional system, a central office (CO) is connectedto a customer's telephone 16 and an ATU-R (ADSL transceiver remote unit)18 or similar end unit at the customer's premise (home, office, etc.)using a copper loop 14 (pair of copper wires). In the CO, a voice switch2, which is generally owned by the ILEC, and a DSLAM (DSL AccessMultiplexers) 4, which in this case is owned by the CLEC, are connectedto a CO splitter 6. As known, the voice switch 2 includes circuitry forproviding POTS (voice) service and the DSLAM 4 includes circuitry forproviding xDSL service to the customer. The DSLAM 4 generally receivesincoming xDSL lines and aggregates the traffic onto high-speed uplinktrunks such as ATM or Frame Relay. The CO splitter 6 is typically foundin a main distribution frame and is generally a passive unit (i.e., nopower).

In greater detail, the CO splitter 6 is used to isolate the voiceservice from the xDSL service. The isolation generated by the COsplitter 6 is important for minimizing interference between the twotypes of services and removing transients. The CO splitter 6 separatesvoice and data band signals received from the copper loop 14 andprovides the respective signals to the voice switch 2 and the DSLAM 4.The CO splitter 6 also combines the voice and data band signals receivedfrom the voice switch 2 and the DSLAM 4 and provides the combinedsignals to the copper loop 14.

The CO splitter 6 includes a low pass filter (LPF) 8 connected to thevoice switch 2 and a high pass filter (HPF) 10 (or DC clockingcapacitors) connected to the DSLAM 4. The LPF 8 filters out higher bandxDSL signals and prevents such signals from interfering with the voiceswitch 2. Likewise, the HPF 10 filters out low band voice signals andprevents such signals from interfering with the DSLAM 4. In other words,the high frequency signals generated by the DSLAM 4 will not interferewith the voice switch 2 because of the LPF 8, and the low frequencysignals generated by the voice switch 2 will not interfere with theDSLAM 4 because of the HPF 10. The voice service typically occupies theband between 0 KHz (DC) to 4 KHz, and the xDSL service occupies somepredetermined band above the voice service such as from 25.9 KHz to 1.1MHz.

A signature S1 12 is also connected to the voice portion of the COsplitter 6. As known, the signature can be used in conjunction with a COtest system for fault identification and localization. The signature S112 is preferably a passive network such as a resistance, capacitor,zeners and diodes combined to from a unique network, which is used toassist in detecting fault conditions, loop length measurements, and thelike. The signature S1 12 can also be active circuit elements thatperform a specific function, as known in the art.

A second remote (RT) splitter 20 having a LPF 22, HPF 24, and signatureSR 26 can be optionally installed in the customer's premise. The LPF 22is connected to the telephone 16 for filtering out high band signals,while the HPF 24 is connected to the ATU-R 18 for filtering out low bandsignals.

FIG. 2 illustrates a diagram of an existing circuit used in theconventional line sharing system as shown in FIG. 1. The LPF 8 generallyincludes series inductors 30-35 and capacitors 42, 44, while the HPF 10generally includes series capacitors 50-53 and inductors 60, 62.

The voice switch 2 typically includes circuitry for interfacing with apair of wires, tip and ring, from the outside plant. As is well known,tip and ring are terms used to describe the two wires that are used toset up a telephony/xDSL connection. The voice switch 2 includesamplifiers 73, 74, connected in series to resistors 71, 72,respectively. The amplifiers 73, 74, and resistors 71, 72, form abalance drive interface circuit to the tip and ring wires. As known, thevoice switch 2 can be implemented with transformers instead ofamplifiers 73, 74. The DSLAM 4 includes a pair of capacitors 81, 82connected in parallel.

With the conventional line sharing system and CO splitter 6 as shown inFIGS. 1-2, the ILEC using the voice switch 2 can continue to test andmaintain the copper loop in the traditional manner, typically usingmechanized loop testing via a Class 5 switch. The LPF 8 in the COsplitter 6 does not significantly interfere with this process. However,it is well known that the CLEC's ability to test and maintain the copperloop for xDSL service is greatly handicapped using the conventional COsplitter 6 because of the HPF 10 and the POTS service. Thus, it is verydifficult for the CLEC to access the copper loop for independent testingand maintenance.

Another disadvantage using the conventional system and method is thatthe CO splitter 6 is typically implemented in a manner that benefits theILECs, which utilize their customized test systems to test and maintainthe POTS portion of the copper loop. The CLECs, which are typically indirect competition with the ILECs for xDSL service, currently do nothave a system and method for independent testing/maintenance of thecopper loop. For example, when the ILEC uses the copper loop for voiceservice, the CLEC is generally prohibited from testing the copper loopin fear of disturbing or interfering with the voice service. If thecopper loop is busy or off-hook (i.e., customer using the telephone),the CLEC will be very hesitant to test the copper loop because suchtesting may terminate the telephone call.

As described above, the conventional CO splitter is generally acceptablefor the ILECs for testing the copper loop for voice service, but it isinadequate for the CLECs for testing the same loop for xDSL service.Accordingly, there is a need for a system and method for providing areliable and effective manner of testing and maintaining the copper loopin the xDSL environment for CLECs. Thus, there is a need for a remotelyactuated splitter bypass system and method for improved testing andmaintenance of the copper loop for the CLECs without interference ordisturbance to/from the POTS service.

SUMMARY OF THE INVENTION

In view of the above-described problems of the prior art, it is anobject of the present invention to provide a remotely actuated splitterbypass system and method.

It is another object of the present invention to provide a system andmethod for implementing a remotely actuated splitter bypass function inthe existing line sharing infrastructure for improved testing andmaintenance for a CLEC.

It is yet another object of the present invention to provide circuitryallowing a CLEC to access the copper loop for testing and maintenancewith minimal interference and disturbance to/from the POTS service.

It is a further object of the present invention to provide a system andmethod for providing a reliable and effective manner for testing andmaintaining a copper loop in the xDSL environment for a CLEC.

It is still a further object of the present invention to provide asystem and method for remotely actuating a bypass function in a splittersuch that testing and maintenance can be performed by a CLEC withoutinterference or disturbance to/from the POTS service.

It is another object of the present invention to provide controlssignals that are carried by the same copper loop pair during testing.

It is yet another object of the present invention to provide an enablesignal to enable multiple pairs of copper loops and when the enablesignal is absent, all splitters automatically revert to the normal modeof operation.

It is a further object of the present invention for providing a methodfor remotely actuating a bypass function in a splitter using a directcontrol approach.

It is yet another object of the present invention for providing a methodfor remotely actuating a bypass function in a splitter using a statemachine control approach.

These and other objects of the present invention are obtained byproviding a remotely actuated splitter bypass (RASB) function that canbe used with a conventional splitter in the current line sharing system.The RASB includes circuitry, working in conjunction with anoff-the-shelf splitter, for testing and maintaining a copper loop by aCLEC with minimal interference and disturbance to/from the POTS service.The splitter bypass operation includes the steps of selecting a copperloop pair for testing, actuating a first relay for monitor mode,actuating a second relay for bypass mode, testing the selected copperloop, and resetting the first and second relays back to normal mode. TheRASB can be implemented using direct control or state machine control.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of the present invention willbecome apparent and more readily appreciated from the following detaileddescription of the presently preferred exemplary embodiments of theinvention taken in conjunction with the accompanying drawings, of which:

FIG. 1 illustrates a simplified block diagram of a conventional linesharing system having a splitter;

FIG. 2 illustrates a diagram of an existing circuit used in theconventional line sharing system as shown in FIG. 1;

FIG. 3A illustrates a block diagram of a line sharing system having asplitter with a remotely actuated splitter bypass function in accordancewith the preferred embodiments of the present invention;

FIG. 3B illustrates a flow diagram showing the splitter bypass operationin accordance with the preferred embodiments of the present invention;

FIG. 3C illustrates a simplified block diagram representing the normalmode in accordance with the preferred embodiments of the presentinvention;

FIG. 3D illustrates a simplified block diagram representing the monitormode in accordance with the preferred embodiments of the presentinvention;

FIG. 3E illustrates a simplified block diagram representing the bypassmode in accordance with the preferred embodiments of the presentinvention;

FIG. 4 illustrates an enable/powering system diagram in accordance withthe preferred embodiments of the present invention;

FIG. 5A illustrates a specific example of the remotely actuated splitterbypass signaling definition in accordance with the first preferredembodiment of the present invention;

FIG. 5B illustrates a signaling sequence of FIG. 5A in accordance withthe first preferred embodiment of the present invention;

FIG. 5C illustrates a functional block diagram of the remote relaycontrol in accordance with the first preferred embodiment of the presentinvention;

FIG. 5D illustrates an example of a detailed circuit diagram of theremote relay control in accordance with the first preferred embodimentof the present invention;

FIG. 6A illustrates a specific example of the remotely actuated splitterbypass signaling definition in accordance with the second preferredembodiment of the present invention;

FIG. 6B illustrates a signaling sequence of FIG. 6A in accordance withthe second preferred embodiment of the present invention;

FIG. 6C illustrates a functional block diagram of the remote relaycontrol in accordance with the second preferred embodiment of thepresent invention;

FIG. 6D illustrates a more detailed block diagram of the state machinein accordance with the second preferred embodiment of the presentinvention;

FIG. 6E illustrates a state table in accordance with the secondpreferred embodiment of the present invention; and

FIG. 6F illustrates an example of a detailed circuit diagram of theremote relay control in accordance with the second preferred embodimentof the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described in greater detail, whichwill serve to further the understanding of the preferred embodiments ofthe present invention. As described elsewhere herein, variousrefinements and substitutions of the various embodiments are possiblebased on the principles and teachings herein.

The preferred embodiments of the present invention will be describedwith reference to FIGS. 3-6, wherein like components and steps aredesignated by like reference numerals throughout the various figures.Further, specific parameters such as potential differences, voltagevalues, circuit layouts, and the like are provided herein, and areintended to be explanatory rather than limiting.

The present invention is directed to a remotely actuated splitter bypass(RASB) function/unit for testing and maintaining copper loops in an xDSLenvironment. In the context of this invention, the term “remotely” isdefined to be anywhere outside the central office splitter. In otherwords, the present invention allows a CLEC to remotely actuating abypass function in the CO splitter such that testing and maintenance canbe performed with minimal interference and disturbance to/from the POTSservice. Alternatively, the CLEC can actuate the bypass function withinthe CO splitter on-site. The RASB can be implemented in two preferredembodiments, direct control and state machine control.

FIG. 3A illustrates a block diagram of a line sharing system having a COsplitter with a RASB function in accordance with the preferredembodiments of the present invention. In this system, the CO isconnected to the customer's telephone 16 and the ATU-R 18 or similar endunit at the customer's premise using the copper loop 14. In the CO, thevoice switch 2 and the DSLAM 4 are connected to a CO splitter 100.

Positioned in between the DSLAM 4 and the CO splitter 100 at the CO is across connect unit 110 such as the CX100 Copper CrossConnect System fromTurnstone Systems, Inc. The CX100 Copper CrossConnect System is aplatform that automates the physical layer infrastructure in the CO,enabling ILECs and CLECs to remotely control, test, and manage thecopper loop 14. Additional information regarding Turnstone System'sCX100 Copper CrossConnect System can be found at the web sitetrunstone.com, which contents are herein incorporated by reference. Itis also noted that other units providing similar functionalities as theCX100 Copper CrossConnect System can be implemented in the presentinvention.

The cross connect 110 includes a test head 112 with a conventionalprocessor board such as a P150 processor (e.g., CX100 CopperCrossConnect System of Turnstone Systems, Inc.). A relay K0 orequivalent functional element can be used to connect the test head 112to the copper loop 14, as described in greater detail later herein. TheCO splitter 100 of the present invention includes the LPF 8, HPF 10, andfirst signature S1 12, similar to that of the prior art CO splitter 6.In addition, the CO splitter 100 includes a first relay K1 or equivalentelement, second relay K2 or equivalent element, resistor R, and secondsignature S2 32. Further included in the CO splitter 100 in between therelay K0 of the cross connect 110 and the first relay K1 is a remoterelay control (RRC) 102. The RRC 102 is connected to the xDSL portion ofthe loop at point A (part of the tip and ring wires) and controls thefirst and second relays K1, K2. A more detailed description and circuitdiagrams of the RRC 102 are provided later herein.

The LPF 8 is connected to the voice switch 2, and the HPF 10 isconnected to the DSLAM 4 via relays K0, K1. The first signature S1 12and the second signature S2 32 are also connected to the voice and xDSLportions of the copper loop, respectively. During operation, an enablesignal (ENABLE), which preferably carries very low power and is commonto n number of splitters, from the cross connect 110 or similar deviceis sent to the CO splitter 100 and n number (i.e., 50, 100, etc.) ofsplitters (OTHERS). In the context of the Turnstone System's CX100Copper CrossConnect System, n is preferably 550, but other arbitrarynumber of copper loops can be used depending on the type of crossconnect used. The RRC 102 is implemented per each copper loop.

FIG. 3B illustrates a flow diagram showing the splitter bypass operationin accordance with the preferred embodiments of the present invention.Reference will be made to both FIGS. 3A and 3B concurrently for a morecomplete understanding of the present system and method.

The steps described in FIG. 3B illustrate the method of testing thecopper loop 14 for the CLEC using the RASB of the present invention.Although other modes of operation are possible using the presentinvention, for simplicity, three modes are described: normal, monitor,and bypass. These three modes are described in greater detail withreference to FIGS. 3C-3E. For example, FIG. 3C illustrates a simplifiedblock diagram of FIG. 3A representing the normal or default mode. TheLPF 8 and HPF 10 are connected to the copper loop in the traditionalsplitter arrangement, similar to that described in the backgroundsection.

Referring back to FIG. 3B, the CLEC uses the test head 112 to select acopper loop 14 pair from n number of copper loop pairs for testing instep 302. When the CLEC has selected the copper loop 14, xDSL service istemporarily shut off, and the test head 112 is connected to the copperloop 14 via the relay K0 in step 304, thereby disconnecting the copperloop 14 from the DSLAM 4. The relays described herein can be switchedvia software, hardware, or combinations thereof, but in certainembodiments as described later herein, the relays are controlled viahardware functions.

In step 306, the first relay K1 is actuated (set) via RRC 102 formonitoring the voice path to determine whether the bypass functionshould be activated. This is accomplished by measuring the voltage onthe copper loop 14 in a non-intrusive manner. As known, differentvoltage values across the copper loop 14 indicate whether the loop isoff-hook (busy) or on-hook. The resistor R in the CO splitter 100minimizes interference to the copper loop 14 during this process. Theresistance value is selected such that the generated noise fromactuating the first relay K1 is acceptable. Generally, the resistor Rhas a high ohm value (>100 k ohms) to allow monitoring without anymaterial disturbance to the copper loop 14 (i.e., provides stability).The first relay K1 can be either a latching or non-latching relay,depending on the specific preferred embodiment.

FIG. 3D illustrates a simplified block diagram representing the monitormode of the present invention. During the monitor mode (step 306), thePOTS service is unaffected, and the test head 112 is connected to thecopper loop 14 while isolating the HPF 10. As discussed above, the testhead 112 is bridged through the resistor R to assure minimalinterference to the POTS service. In the monitor mode, the CLEC cancheck the DC and voice band frequencies for an off-hook or on-hookcondition so that testing can be performed on the copper loop withoutinterfering with an active POTS telephone call.

In step 308, if the voice path is determined to be off-hook, thentesting is avoided in step 310. On the other hand, if the voice path ison-hook in step 308, then the second relay K2 is actuated (set) via RRC102 to enable the bypass function for testing in step is 312.

FIG. 3E illustrates a simplified block diagram representing the bypassmode of the present invention. In the bypass mode (step 312), the POTSservice is disconnected from the copper loop, and the xDSL service isreconnected directly to the copper loop. As illustrated, the LPF 8, HPF10, signatures S1 12, S2 32 are isolated from the rest of the circuitduring the bypass mode. In this manner, the CLEC can obtain full accessto the copper loop 14 in the outside plant for testing withoutinterference to/from the LPF 8, HPF 10, and/or the voice switch 2. Whenthe second relay K2 is actuated, testing is performed for apredetermined period (i.e., 30 seconds) via the test head 112 in step314. The resistor R is shorted out during the bypass mode, and testingis performed during the bypass mode.

Preferably, the second relay K2 is a non-latching type relay. It isimportant that the second relay K2 is non-latching because this providesa fail-safe design in case power is lost as the system automaticallyresets back to the normal mode. This aspect of the invention isdescribed in more detail later herein. Once testing is completed, thefirst and second relays K1, K2 are reset in step 316 via RRC 102 tonormal mode and the signature S2 32 is checked in step 316. Thesignature S2 could also be checked before step 306; however, this maycause noise interference during a busy POTS call.

FIG. 4 illustrates an enable/powering system diagram in accordance withthe preferred embodiments of the present invention. In the CO, onecopper loop pair from n pairs (where n is some arbitrary number) is usedto transmit enable signals from the test head to the RRC and n number ofCO splitters. Preferably, only one of n splitters is allowed to be inactive bypass mode per test head. In this specific example, it isassumed that one copper loop pair is 26 gauge and that the distance fromthe cross connect 110 to a splitter shelf is a maximum of 1000 feet. Itis also assumed that a standard CO battery voltage of 50±6 is used inthis implementation.

A signature S is used to assure that the correct copper loop pair ishooked up before switching on the power source. The cross connect 110will check the signature S before the enable signal is generated. Theenabled copper loop terminates with a 5W, ±5 V DC/DC, and the averagepower per splitter allocation is approximately 24 mV (2.4 mA for ±5V).The ±5V could be used to power the circuitry for the n number ofsplitters.

As described above, the RASB method and system of the present inventioncan be implemented in two preferred embodiments, using a direct controlapproach and a state machine approach. FIGS. 5A-5D illustrate the firstpreferred embodiment, and FIGS. 6A-6F illustrate the second preferredembodiment of the present invention. Referring back to FIG. 3A, thesetwo preferred embodiments relate to the design and the implementation ofthe control signals to the first and second relays K1, K2 using the RRC(remote relay control) 102. Thus, design implementation of the LPF 8,HPF 10, signature S1 12, and signature S2 32 will not be discussed ingreat detail hereinafter, as these components are known in the priorart. Further, although the CO splitter described herein is implementedwith two relays, it is understood that more or less than two relays inthe CO splitter can be used herein and is within the scope of thepresent invention.

FIG. 5A illustrates a specific example of the RASB signaling definitionin accordance with the first preferred embodiment of the presentinvention. As known, a power source in the CO can be connected to thetip, ring, and/or ground wires. In the present invention, voltages areapplied to the tip and ring wires with respect to the ground wire.

In the first preferred embodiment, relays are “set” or actuated when anappropriate positive voltage magnitude is applied from tip and ringwires with respect to the ground wire. Conversely, relays are “reset”when an appropriate negative voltage magnitude is applied from tip andring wires with respect to the ground wire. The polarity of the voltagesfor set and reset conditions can be interchangeable by a person skill inthis art (i.e., set having negative polarities and reset having positivepolarities).

In greater detail, each relay can be set with a positive polarity, usingsome arbitrary voltage range, which range is pre-defined/pre-designed.Conversely, each relay can be reset with a negative polarity, using somearbitrary voltage range, which range again is pre-defined/pre-designed.In additional, a particular voltage range that sets a particular relayor relays includes a reciprocal voltage range to reset another relay orrelays. For example, one can set relay K1 in the +62 to +70 voltagerange, and reset the relay K3 using the −62 to −70 voltage range. Inanother example, relays K1 and K2 can be set using the +73 to +83voltage range, and relays K3 and K2 can be reset using the −73 to −83voltage range, respectively. In this manner, multiple relays can beremotely actuated from the CO by providing different voltages andpolarities. It is also noted that in FIG. 5A, the voltage ranges andpolarities are for illustrative purposes only and other practicalvoltage ranges and polarities can be substituted for those illustrated.

The signaling definition allows the relays to be set sequentially suchthat relay K1 is set first and then relay K2, and so on. For example, itis important that relay K1 is set first for monitor mode before settingrelay K2 for bypass mode. This is accomplished by setting the relay K1in a lower voltage range than relay K1. Likewise, the relays aresequentially reset such that relay K2 is reset first and then relay K1,and so on. This is accomplished by resetting relay K1 in a higherabsolute magnitude voltage range than relay K2. This assures that thesignaling path is not cut off pre-maturely during the relays' settingand resetting processes. In other words, the present schema allows thefirst set relay K1 to be the last reset relay K1, and the last set relayK3 to be the first reset relay K3.

FIG. 5B illustrates a signaling sequence of FIG. 5A in accordance withthe first preferred embodiment of the present invention. As shown inFIG. 5B, the circuit is generally in normal mode, which mode refers tothe traditional line sharing system.

When copper loop testing is initiated from the xDSL circuit, theselected copper loop pair is connected to the test head. A first signal(e.g., +68 volts) is used to set relay K1. When the relay K1 is set,this indicates the monitor mode. The copper loop is connected to thetest head through resistor R. The test head checks for DC voltage andvoice band signals for monitoring whether the copper loop is off-hook oron-hook. If off-hook, the system aborts accessing this loop for testing.If it is on-hook, a second signal (e.g., +78 volts) is used to set thesecond relay K2, which provides the test head direct access to thecopper loop while bypassing the CO splitter. This puts the system in thebypass mode, which enables loop testing by the test head. When looptesting is completed, a third voltage signal (e.g., −88V) is used toreset the relays back to normal mode.

FIG. 5C illustrates a functional block diagram of the RRC in accordancewith the first preferred embodiment of the present invention. The RRC102 a includes a Signal Conditioning block (SC) 502 connected to a firstLevel Sense (LS1) 504, second Level Sense (LS2) 506, reset Level Sense(LSR) 508, and tip and ring wires at point A. The LS1 504 detects thepresence of the first voltage signal (e.g., +68V), the LS2 506 detectsthe presence of the second voltage signal (e.g., +78V), and the LSR 508detects the presence of the third voltage signal (e.g., −88V). The LS1504 is further connected to and controls the first latching relay K1104. V_(r1) is the reference voltage for LS1 504, V_(r2) is thereference voltage for LS2 506, and V_(rr) is the reference voltage forLSR 508. The reference voltages are pre-defined and can also beadjustable depending on the type and values of the hardware componentsused in a particular circuitry.

The relay K1 104 is preferably a latching-type relay (includes memory),which could be either electromechanical or semiconductor solid state.The latching-type feature is essential in that once the applied voltageexceeds a pre-defined reference voltage, a constant voltage is appliedto actuate the relay K1. The latching-type feature is also essentialbecause it can then allow application of a voltage across the T and R toperform other functions without affecting the first relay K1.

A latch (LH-1) 510 is connected to the LS2 506 and controls the secondnon-latching relay K2 106. A “watch-dog” timer (TMR) 512 is used in caseof a system malfunction. After a timeout period (i.e., 60 seconds), theTMR 512 automatically resets the relays K1 104, K2 106 back to thenormal mode.

During operation, the test head sends a first voltage signal to the tipand ring wires. The SC 502 conditions the signal and inputs it to theLS1 504, LS2 506, and LSR 508. The first voltage signal is detected byLS1 504, which in turns sets the first relay K1 104. This indicates themonitor mode, and the test head monitors the copper loop.

If the copper loop is on-hook, the test head generates and sends asecond voltage signal to the tip and ring wires. After signalconditioning by the SC 502, the second voltage signal is detected by theLS2 506. This signal is then outputted by the LS2 506 and sent to theinput S of the flip flop LH-1 510;. The LH-1 510 then outputs a logical1 via output Q to the AND gate 514 and TMR 512, producing a secondlogical 1 at the TMR's output Q. The logical 1 outputs from both theLH-1 510 and TMR 512 are sent to the AND gate 514 to produce a logical 1at the AND gate's output to set the second relay K2 106. The system isnow in the bypass mode and loop testing can be performed.

When loop testing is completed, the test head sends a third voltagesignal to the tip and ring wires. This signal is detected by the LSR 508after signal conditioning via the SC 502. The LSR 508 in turn sends thethird voltage signal to reset relay K1 104 and to the LH-1 510, which inturn resets relays K2 106, K1 104 in a sequential or simultaneous mannerfor this particular case. The system is now back in the normal mode.

In the event that the third reset voltage signal is not received by orsent to the LH-1 510 due to some malfunction, the relay K2 106automatically resets itself back to the normal mode via the TMR 512,thereby providing a fail-safe bypass function and POTS service isconnected back to the splitter in the normal mode.

FIG. 5D illustrates an example of a detailed circuit diagram of the RRC102 a in accordance with the first preferred embodiment of the presentinvention. Reference will be made concurrently to FIGS. 5C and 5D for amore complete understanding of the detailed circuit diagram.

Functionally, the LS1 504 includes transistors Q1, Q2, Q5, Q6, andresistors R4, R5. The LS2 506 is represented by transistors Q9-Q11, andresistors R12, R13, and the LSR 508 is represented by transistors Q3,Q4, Q7, Q8, and resistors R6, R7, R11. Next, the LH-1 510 circuitryconsists of transistors Q12-Q14, resistors R14-R20, and diodes D3, D4.The TMR 512 includes transistors QI5-Q17, resistors R21-R24, R27-R28,and capacitor C2 (used for switching as it is charged up). The AND gate514 includes transistors Q18-Q21, resistors R25-R26, R29-R31, and diodeD5. The SC 502 consists of resistors R1-R3 and capacitor C1.

FIG. 6A illustrates a specific example of the RASB signaling definitionin accordance with the second preferred embodiment of the presentinvention. The second preferred embodiment is directed to the statemachine control. Similar to the first preferred embodiment, voltages areapplied to the tip and ring wires with respect to the ground wire.

The RASB signaling definition of the second preferred embodiment issimilar to the first preferred embodiment in that the relays are “set”or actuated when an appropriate voltage magnitude and polarity isapplied from tip and ring wires with respect to the ground wire, andrelays are “reset” when an appropriate voltage magnitude and polarity isapplied from tip and ring wires with respect to the ground wire. Thepolarity of the voltages for set and reset conditions can beinterchangeable by a person skill in this art by appropriately designingthe circuit (i.e., set having negative polarities and reset havingpositive polarities).

In greater detail, each relay can be set with a positive polarity, usingsome arbitrary voltage range, which range is pre-defined/pre-designed.Conversely, each relay can be reset with a negative polarity, using somearbitrary voltage range, which range again is pre-defined/pre-designed.

In the state machine approach, the first and second relays K1 and K2 canbe set sequentially using the +62 to +70 voltage range. Likewise, theserelays can be reset sequentially or simultaneously for this particularembodiment from the second relay K2 to the first relay K1 in the −73 to−83 voltage range. In this manner, multiple relays can be remotelyactuated from the CO by providing different voltages and polarities. Itis further noted that in FIG. 6A, the voltage ranges are forillustrative purposes only and other practical voltage ranges can besubstituted for those illustrated.

The signaling definition allows the relays to be set sequentially suchthat relay K1 is set first and then relay K2, and so on. For example, itis important that the relay K1 is set first for monitor mode beforesetting relay K2 for bypass mode. This is accomplished by sequentiallysetting the relay K1 first and then the relay K2. Likewise, the relaysare sequentially reset such that relay K2 is reset first and then relayK1, and so on. This assures that the signaling path is not cut offpre-maturely during the relays' setting and resetting processes. Forthis particular case, sequential reset is not necessary.

FIG. 6B illustrates a signaling sequence of FIG. 6A in accordance withthe second preferred embodiment of the present invention. As shown inFIG. 6B, the circuit is generally in normal mode, which mode refers tothe traditional line sharing system.

When copper loop testing is initiated from the xDSL circuit, theselected copper loop pair is connected to the test head. A first signal(e.g., +68 volts) is generated to set relay K1, which indicates themonitor mode. The loop is then connected to the test head throughresistor R. The test head checks for DC voltage and voice band signalsfor monitoring whether the copper loop is off-hook or on-hook. Ifoff-hook, the system aborts accessing this copper loop for testing. Ifit is on-hook, a second voltage signal (e.g., +68 volts) is sent to setsecond relay K2, which provides the test head direct access to thecopper loop while bypassing the CO splitter. Thus, two sequentialvoltage signals of equal value are used to set the relays K1, K2. Thisputs the system in the bypass mode, which enables loop testing by-thetest head. When loop testing is completed, a third voltage signal (e.g.,−88V) is used to reset the relays back to normal mode.

FIG. 6C illustrates a functional block diagram of the RRC in accordancewith the second preferred embodiment of the present invention. The RRC102 b includes a Signal Conditioning block (SC) 602 connected to a resetLevel Sense (LSR) 604, Level Sense Set (LSS) 606, and tip and ring wiresat point A. The RRC 102 b also includes a State Machine (SM) 608, timer(TMR) 610, and an AND gate 612. First and second relays K1 104, K2 106are preferably non-latching (standard) type relays. The “watch-dog”timer (TMR) 610 is used in case of a system malfunction. After a timeoutperiod (i.e., 60 seconds), the TMR 610 automatically resets the relaysK1 104, K2 106 back to the normal mode. V_(rr) is the reference voltagefor LSR 604, and V_(rs) is the reference voltage for LSS 606.

When the system is in the normal mode, the outputs B0 and B1 of the SM608 are represented by logical 0s. During operation from normal mode tomonitor mode, the test head sends a first voltage signal (e.g., +68V) tothe tip and ring wires at point A. The SC 602 conditions the signalinputs it to the LSR 604 and LSS 606. The first voltage signal isdetected by the LSS 606, which in turn sends the voltage signal to theSM 608 at input CP to increment the SM 608 from normal to monitor mode.The output B0 of the SM 608 is now represented by a logical 1 and isused to set the first relay K1 104, thereby actuating the monitor mode.Meanwhile, the output from B0 of SM 608 is sent to the input S of theTMR 610 to begin the timing signal.

During the monitor mode, if the copper loop is determined to be on-hook,the test head generates and sends a second voltage signal (e.g., +68)equal to the first voltage signal to the tip and ring wires. Aftersignal conditioning by the SC 602, the second voltage signal is detectedby the LSS 606 to increment the SM 608 from monitor to bypass mode byoutputting a logical 1 at the B1 output.

The logical 1 outputs from both B0 of SM 608 and Q of TMR 610 are sentto the AND gate 612 to produce a logical 1 at the AND gate's output toset the second relay K2 106. The system is now in the bypass mode andloop testing can be performed.

When loop testing is completed, the test head sends a third voltagesignal (e.g., −88V) to the tip and ring wires. The third voltage signalis detected by the LSR 604 after signal conditioning via the SC 602. TheLSR 604 in turn sends the third voltage signal to the SM 608, which inturn resets first and second relays K2 106, K1 104 by generating logical0s at B0 and B1. The system is now in the normal mode.

In the event that the third reset voltage signal is not received by orsent to the LSR 604 or SM 608 due to some malfunction, the relay K2 106automatically resets itself back to the normal mode via the TMR 610.

FIG. 6D illustrates a more detailed block diagram of the state machinein accordance with the second preferred embodiment of the presentinvention. The state machine is represented by FF0 (flip flop 0) 702 andFF1 (flip flop 1) 704. The voltage signals from LSR 604 and LSS 606 aresent to the FF0 702 and FF1 704 at inputs C (clear input) and CP (clockinput), respectively. The output B0 is generated from outputs Q1 of FF0702, and the output B1 is generated from output Q2 of FF1 704.

FIG. 6E illustrates a state table in accordance with the secondpreferred embodiment of the present invention. As shown, the normal modeis active when the output B0 and B1 signals are logical 0, whichrepresents that the first and second relays K1, K2, are not set. Themonitor mode is active when the output B0 signal is a logical 1 and theoutput B1 signal is a logical 0, which represents that the first relayK1 is set and the second relay K2 is not set. The bypass mode is activewhen both the output B0 and B1 signals are logical 1, which representsthat the first and second relays K1, K2 are set.

FIG. 6F illustrates an example of a detailed circuit diagram of the RRC102 b in accordance with the second preferred embodiment of the presentinvention. Reference will be made concurrently to FIGS. 6C and 6D for amore complete understanding of the detailed circuit diagram of FIG. 6F.

Functionally, the SM 608 includes FF1 and FF2. The LSR 604 isrepresented operational amplifier C2, and the LSS 606 s is representedby operational amplifier C1. Next, the TMR 610 includes transistorsQ1-Q4, resistors R9-R14, and capacitor C2 (used for switching as it ischarged up). The AND gate 612 includes transistors Q6, Q7, and resistorR16. The SC 602 consists of resistors R1, R2, R19 and capacitor C1.

In other embodiments, other components can be substituted for thespecific components described herein so long as these components performessentially identical functions as described herein.

In the previous descriptions, numerous specific details are set forth,such as specific functions, components, etc., to provide a thoroughunderstanding of the present invention. However, as one having ordinaryskill in the art would recognize, the present invention can be practicedwithout resorting to the details specifically set forth.

Although only the above embodiments have been described in detail above,those skilled in the art will readily appreciate that many modificationsof the exemplary embodiments are possible without materially departingfrom the novel teachings and advantages of this invention.

I claim:
 1. A splitter connected to a voice port, a xDSL port, and anoutside copper loop for providing POTS service and xDSL service to acustomer premise, the splitter comprising: a low pass filter coupled tothe voice port; a first signature coupled to the low pass filter formonitoring the low pass filter; a high pass filter coupled to the xDSLport; a second signature coupled to the high pass filter for monitoringthe high pass filter; a first relay for monitoring a voice path; asecond relay for isolating the high pass filter and the low pass filter,enabling testing of the copper loop from the xDSL port; and a remoterelay control for controlling the first and second relays.
 2. A splitteraccording to claim 1, wherein the first relay comprises one of alatching and non-latching relay.
 3. A splitter according to claim 1,wherein the second relay comprises a non-latching relay.
 4. A splitteraccording to claim 1, wherein the remote relay control comprises: asignaling conditioner for conditioning voltage signals; a first levelsensor coupled to the signaling conditioner for detecting a firstvoltage signal and for setting the first relay; a second level sensorcoupled to the signaling conditioner for detecting a second voltagesignal; a third level sensor coupled to the signaling conditioner fordetecting a third voltage signal; a latch coupled to the second levelsensor for setting the second relay; and a timer coupled to the latchand the third level sensor for resetting the first and second relays. 5.A splitter according to claim 4, wherein the first voltage signal isused to set the first relay.
 6. A splitter according to claim 5, whereinsetting the first relay provides a monitor mode.
 7. A splitter accordingto claim 5, wherein the second voltage signal is used to set the secondrelay.
 8. A splitter according to claim 6, wherein setting the first andsecond relays provides a bypass mode.
 9. A splitter according to claim4, wherein the third voltage signal is used to reset the first andsecond relays.
 10. A splitter according to claim 9, wherein resettingthe first and second relays provides a normal mode.
 11. A splitteraccording to claim 4, wherein the first and second voltage signalsincludes a first polarity and the third voltage signal includes a secondpolarity opposite the first polarity.
 12. A splitter according to claim4, wherein the timer automatically resets the first and second relaysafter a timeout period.
 13. A splitter according to claim 1, wherein theremote relay control comprises: a signaling conditioner for conditioningvoltage signals; a level set sensor coupled to the signaling conditionerfor detecting first and second voltage signals; a reset level sensorcoupled to the signaling conditioner for detecting a third voltagesignal; a state machine coupled to the level set sensor and the resetlevel sensor for controlling the first and second relays; and a timercoupled to the state machine and the reset level sensor for resettingthe first and second relays.
 14. A splitter according to claim 13,wherein the first and second voltage signals are used to set the firstand second relays, respectively.
 15. A splitter according to claim 14,wherein the first and second voltage signals are the same voltagesignal.
 16. A splitter according to claim 14, wherein setting the firstrelay provides a monitor mode.
 17. A splitter according to claim 16,wherein setting the first and second relays provides a bypass mode. 18.A splitter according to claim 14, wherein the third voltage signal isused to reset the first and second relays.
 19. A splitter according toclaim 18, wherein resetting the first and second relays provides anormal mode.
 20. A splitter according to claim 13, wherein the first andsecond voltage signals includes a first polarity and the third voltagesignal includes a second polarity opposite the first polarity.
 21. Asplitter according to claim 13, wherein the timer automatically resetsthe first and second relays after a timeout period.